This invention relates to improved methods, apparatus, and computer program products for applications such as operating and optimizing process equipment, process operations, process recipes for applications such as processing workpieces and performing general process operations. More particularly, embodiments of the present invention relate to processing workpieces for electronic device fabrication and other high value product production.
Some processes for processing workpieces, such as electronic device manufacturing, are extremely complex. Considering, as an example, the application of fabricating electronic devices, the process may involve temperature sensitive processes such as selective deposition and removal of various materials on a workpiece such as a silicon wafer. The manufacture of a typical integrated circuit or chip may involve hundreds of individual processing steps. In order to make integrated circuits reliably and economically, it is essential for each product wafer to experience the same conditions in each of the many process steps. Complex, expensive processing tools of various kinds perform these processing steps. A factory will typically have several tools of each type. As a result, it becomes very desirable to have all the tools of a given type behave as similarly as possible, i.e. that each of these tools match.
Indeed, the problem of getting process tools to provide substantially equivalent process results is well known in industries such as those for fabricating electronic devices such as integrated circuits. Furthermore, tool-matching problems can occur in various situations. For example, after a period of use, the performance results of some process tools drift over time. Consequently, for some applications it is equally important to make sure that this drift is small, or equivalently, that the behavior of a tool on a given day matches with the behavior on another day. Because of the need to have extreme reliability and repeatability, and to have high manufacturing throughput, it is essential that the matching technique be automated by means of a computer program. Moreover, because of the exacting tolerances required of modern integrated circuits, it is important that the matching technique be able to automatically detect small differences between the performances of process tools.
Clearly, there are numerous applications requiring reliable and efficient methods and apparatus for one or more tasks such as fingerprinting, matching, comparing, and automatically characterizing processing tools. In addition, there is a need for methods and apparatus capable of using spatially resolved time-series data for performing such tasks. One example of an important application for the methods and apparatus is the processing of workpieces such as semiconductor wafers, flatpanel displays, and other electronic devices.